Cystic fibrosis (CF) is an autosomal recessive disease and a prime candidate for gene therapy. CF represents a major target for gene therapy research as the airway epithelium is relatively isolated and, theoretically, readily accessible by nebulized vectors. However, CF gene therapy faces the same obstacles that prevent the widespread use of gene therapy for other diseases;of 1300gene therapy clinical trials conducted worldwide to-date, barely three percent of these have been approved for phase three clinical trials. Clinical application of gene therapy is hindered by lack of safe and efficient delivery methods. Non-viral vectors can provide the requisite safety, but design of efficient materials is limited by a lack of understanding of the intracellular mechanisms of gene delivery. Many approaches to vector design are empirical, as data provided in the literature do not definitively provide robust model criteria for the design of gene delivery vehicles. Therefore, the principal objective of this proposal is to elucidate design criteria for safe and efficient gene delivery vehicles that will be used to construct a model for epithelial airway gene delivery. Specifically, this study will examine the internalization mechanisms and intracellular behavior of integrin-mediated gene transfer vectors. The specific aims of this proposal are to determine (1) the effectiveness of vector-ligand conjugation for targeted, receptor-mediated internalization at the cell surface;(2) the roles of endocytic vesicle acidification, trafficking kinetics, and processing pathways- namely clathrin and caveolin mediated vesicle transport - in vector escape and subsequent DNA unpackaging from the delivery vehicle;and (3) the interplay of molecular motors and cytoskeletal structures in endocytic vesicle trafficking of vectors. Correlating targeted delivery efficiency and intracellular trafficking studies will produce insightful structure-property relationships that will aid in the rational design of gene delivery vehicles. This study will focus on the design of synthetic, targeted, non-viral vectors that are minimally cytotoxic and easily produced. Preliminary results have established generalizable principles for the design of targeted vectors to different endocytic pathways from an epithelial (HeLa) cell model using prototypical ligands transferrin and folate. The long term goal is to use these principles to affect targeted airway gene delivery in human lung and bronchial epithelial cell lines. The clinical goal of gene therapy is to treat disease by delivering therapeutic genes to a patient in a highly efficient, specific, and safe manner. PUBLICH HEALTH RELEVANCE: The aims described herein seek to elucidate design criteria for delivery approaches in human airway tissue, and ultimately, the development of cystic fibrosis treatment.